adjective

1. unreasonably determined to have one's own way; not yielding to reason or plea; stubborn; dogged; mulish
2. resisting remedy or treatment an obstinate fever
3. not easily subdued, ended, etc.

Etymology: ME < L obstinatus, pp. of obstinare, to resolve on < obstare, to stand against, oppose < ob- (see ob-) + stare, to stand